1. Field of the Invention
The present invention relates to improved elastomeric compositions of matter comprising an elastomer (e.g. a natural or synthetic rubber), a filler (preferably comprising a silica), and a coupling agent for coupling said elastomer to said filler, said coupling agent comprising at least one silane and at least one succinimide, the succinimide preferably being an alkenyl succinimide which is the condensation product of a polyamine with an alkenyl succinic anhydride. The invention also relates to the novel silane/succinimide coupling agents, and to shaped articles prepared from the elastomeric compositions of the invention.
2. Description of the Prior Art
Precipitated silicas have long been known to have good reinforcing power, that is to say, to improve the technological properties of vulcanized materials, such as tensile strength, hardness, modulus, resistance to abrasion, resistance to tearing, and the like. However, there are several ways in which the vulcanized materials reinforced with commercial silicas are inferior to those filled with the best carbon blacks, e.g. less resistance to abrasion, greater retentivity after deformation, and greater dissipation of energy, and thus more heating when under dynamic strain.
Various ways of improving the performance of elastomers filled with silica have therefore been proposed. One general method for overcoming these disadvantages consists of improving the filler-elastomer bond, by using a bonding or coupling agent. However, this method necessitates selecting a coupling agent that is both cheap and effective, quite apart from the fact that it must not bring with it its own inherent disadvantages.
The effectiveness of coupling agents of the silane and particularly the mercapto-silane type is well-known and has been described in the literature, particularly in Rubber World, October 1970, pp. 53-58 and European Rubber Journal, March 1974, pp. 37-46.
Unfortunately, the use of silane coupling agents suffers from two very serious disadvantages: first, their very high cost as compared to that of the filler proper and, secondly, their odor, which virtually prevents their use beyond the threshold of 1% by weight relative to the elastomer.